Thermal history evaluation of low-grade altered or metamorphic rocks using thermometer based on geological kinetic indicator -estimation of duration of thermal event-

在松辽盆地应用裂变粘结退火动力学进行了热史评价。首先，为了确定白垩纪地层的最大沉积年龄，对中部凹陷区、西侧及周边地区钻井采集的沉积岩进行了锆石、磷灰石裂变径迹年龄测定和裂变径迹长度测量。白垩纪地层的锆石和磷灰石FT年龄和FT长度表明，源区在120-100 Ma具有相当均匀的冷却历史。这意味着盆地附近大兴安岭的火山岩在沉积后不久就被侵蚀了，并向松辽盆地方向进行了重新加工。而盆地凹陷深部岩心样品中的磷灰石则表现出强烈的退火年龄。其次，为了估算后白垩纪的古地温，按以下步骤分析了各深度磷灰石的年轻化趋势。(1)为…创造埋葬历史采用Sclater和Cristie的压实模型，(2)假设古地温梯度不变，(3)利用正演模拟技术估计每个样品的热史上的年轻化趋势，(4)预测的FT年轻化趋势与观测到的年轻化趋势进行统计检验。结果表明，拟合良好的古地温线为40-45℃/Km，地温线的持续时间估计为数十MYR。另一方面，以日本绿凝灰岩地区的油盆为例，分析了广泛成熟度指标--甲基菲指数(MPI)的变化规律及其与Ro%的关系。对于所有的岩石样品，在成熟区(%Ro=0.5-1.9)，MPI从0.7增加到4.2，在过成熟区(%Ro=1.9-4.5)，MPI从4.2下降到1.3。用地球化学动力学的方法讨论了这些趋势的上斜率，认为MPI的变化取决于中间体MPI的产生和从α-异构体到β-异构体的甲基转移。较少

Thermal history evaluation using fission tack annealing kinetics was applied for the Songliao Basin. Firstly, to constrain the maximum deposition age of the Cretaceous Strata, zircon and apatite fission track dating and fission track length measurement have been carried out for the sedimentary rocks collected from the drilling well in the central depression area, western flank area and surrounding areas. Zircon and apatite FT ages and FT lengths for Cretaceous Strata suggest that the source region has a fairly homogeneous cooling history at 120-100 Ma. This means that the volcanic rocks in the Dahinganling Mountains near the basin were eroded soon after their deposition and were reworked toward the Songliao Basin. While, apatites from deep core sample at depression part of the basin show severely annealed ages. Secondary, to estimate post-Cretaceous paleo-geotherm, the younging trend of apatites from each depth were analyzed according to the following step. (1) Making burial history fo … More r each core sample using Sclater and Cristie's compaction model, (2) supposing the hypothetical constant paleo-geothermal gradients, (3) estimate younging trends for each sample's thermal histories using forward modeling technique, (4) statistical check between the predicted FT younging trend and observed younging trend. As a result, the good fitted paleo-geotherm was estimated for 40-45 ℃/km and several tens of Myrs was estimated for the duration of the geotherm. On the other hand, the methylphenanthrene index (MPI), wide-range maturation indicator, was analyzed especially from oil basin at green-tuff region in Japan to know the variation of MPI and its relation to Ro %. For all rock samples, the MPI showed increase from 0.7 to 4.2 in the mature zone (%Ro=0.5-1.9 and decrease from 4.2 to 1.3 in the over-mature zone %Ro=1.9-4.5. The upper slope in these trends was discussed by means of geochemical kinetics, suggesting that the MPI change depend on production of intermediate MPI and the methyl-shift from alpha-isomer to beta isomer. Less